1. Field of the Invention
The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus realizing improved operability.
2. Description of the Related Art
In recent years, a remote panel function has been proposed in an image forming apparatus such as an MFP (Multifunction Peripheral). The remote panel function is for receiving an operation of the image forming apparatus at a remote terminal that is connected to the image forming apparatus by way of a network, transmitting information on the operation from the remote terminal to the image forming apparatus, executing processing in accordance with the information on the operation at the image forming apparatus, and transmitting, to the remote terminal, information on a screen updated due to the processing. The remote panel function enables operations to an operation panel of the image forming apparatus with use of the remote terminal.
With the remote panel function, it may take time for the image forming apparatus to execute processing in accordance with the operation executed at the remote terminal, which will delay update to a screen displayed on the remote terminal. Therefore, in a case where the remote terminal receives a new operation from a user before the remote terminal updates the displayed screen, the screen displayed on the remote terminal may transit to a screen not desired by the user depending on timing of updating the displayed screen. As a result, the remote terminal may erroneously operate (the operation by the user may cause an erroneous operation) in some cases.
Assume a case where the remote terminal successively receives operations to a plurality of keys from a user on a screen initially displayed. In this case, the image forming apparatus executes processing in accordance with the initial key operation by the user, and updates the screen displayed on the remote terminal in accordance with the processing (transits to an updated screen). However, the image forming apparatus determines that the subsequent key operation by the user should have been performed on the updated screen, despite the fact that the subsequent key operation has been performed by the user while viewing the initially displayed screen. As a result, the image forming apparatus executes screen processing unintended by the user, thereby to cause an erroneous operation.
There have been conventionally proposed methods of preventing such an erroneous operation as described above.
FIG. 27 is a sequence diagram showing conventional communication between an MFP having a remote panel function and a remote terminal.
With reference to FIG. 27, when the MFP transmits, to the remote terminal, information on a screen currently displayed on an operation panel (apparatus screen information), the remote terminal displays, in accordance with the information, a screen same as the screen currently displayed on the operation panel. Upon receipt of a key operation from a user, the remote terminal transmits information on the key operation to the MFP. Upon receipt of the information on the key operation, the MFP comes into a key reception inhibition state (the state for not receiving a subsequent key operation), and executes processing in accordance with the key operation. The MFP transmits, to the remote terminal, data of a screen updated due to the processing. When the remote terminal updates the displayed screen in accordance with the data thus received, the remote terminal transmits an update completion report to the MFP. Upon receipt of the update completion report, the MFP cancels the key reception inhibition state.
In the sequence diagram mentioned above, the MFP does not receive input of a subsequent operation from the remote terminal until completion of update of the screen.
In addition to the technique described above, Document 1 discloses a display control apparatus that causes an operation unit to stop receiving, in a case where the operation unit receives an operation instruction corresponding to operation screens successively switched and displayed on a display unit of an electric appliance or the like, any operation instruction corresponding to a switched operation screen, in a predetermined period of time from completion of reception by the operation unit to switching of the operation screen to a different operation screen.
Document 2 discloses an image forming apparatus for distributing a web page to a terminal device of an image forming apparatus. The image forming apparatus includes operation screen control means for controlling an operation screen displayed on the image forming apparatus and an operation screen displayed as a web page on the terminal device of the image forming apparatus such that use of one of the operation screens is inhibited while the other operation screen is being used.
Document 3 discloses a remote control system that includes a control target computer and a control terminal for transmitting input information to the control target computer, wherein the control target computer transmits, to the control terminal, displayed image information displayed on a display unit of the control target computer in accordance with the input information transmitted from the control terminal, and the control terminal displays, on a display unit of the control terminal, the displayed image information thus transmitted. In this system, the control target computer includes a display data processor for processing displayed image information displayed on the display unit of the control target computer in accordance with display capacity information on the control terminal and a transfer rate of data in communication with the control terminal, and a server communicator for transmitting, to the control terminal, the displayed image information processed by the display data processor.    Document 1: Japanese Patent Publication Laying-Open No. 2010-224976    Document 2: Japanese Patent Publication Laying-Open No. 2006-86642    Document 3: Japanese Patent Publication Laying-Open No. 2004-187062
In the conventional image forming apparatus, input of any subsequent operation is not received from the remote terminal until completion of update of a screen. Therefore, a user cannot successively operate the remote terminal, which deteriorates operability. For example, in a case where the remote terminal receives an operation to execute script processing which is a processing having a batch of setting information for execution of specific processing, the remote terminal successively transmits, to the image forming apparatus, information on a series of operations for the processing, without waiting for reception of data of an updated screen. Nevertheless, these operations are blocked and cancelled by the image forming apparatus. In a state where the remote terminal displays list data such as a list of facsimile transmission addresses, if the remote terminal receives a flick operation to scroll a screen, the image forming apparatus does not receive the operation until the remote terminal displays a scrolled screen. Therefore, it is not possible to halfway stop scrolling.